Gear Ratio Calculator
Calculate single- or multiple-stage gear ratios and output RPM.
Runs in your browser — nothing is uploaded—
Details
How to use Gear Ratio Calculator
- Enter your values — the unit for each field is shown next to it.
- The result updates instantly as you type.
- Copy the results, or change inputs to compare scenarios.
Formula & assumptions
Overall ratio = ∏(driven teeth / driving teeth); output RPM = input RPM / ratio
Example: 20 driving teeth and 40 driven teeth give 2:1; 3,000 RPM becomes 1,500 RPM.
Questions
Does this calculate torque?
It gives ideal speed ratios. Real torque depends on input torque, transmission losses and the mechanism.